The filming is cheesy. Some of the actors overact. Some of the actions are unexplained and unexplainable. But...

This movie is in the mode of the psychological dramas of the 50s.

It is a morality play. Similar to the movie in which a "method" actor becomes the evil character he portrays on stage, Ed is forced to watch slasher movies because he is the film editor. It gives him a nervous breakdown which leads to a complete psychotic break.